Jason Tochi of 24XX fame wrote a great post a little while ago about what he calls the three layers of rules: social, fictional, and abstract. If you’re interested in game design it’s a great way to think about things, especially in more rules light games. Where do the unspoken rules go? Probably to the social and fictional layers.
https://pretendo.games/2022/04/15/three-layers-of-rpg-rules/